Method and apparatus for producing three-dimensional picture

ABSTRACT

The three-dimensional television set comprises a closed apparatus (12) with a 3D video signal input and/or arial input, and a laser source (22), a modulator (24) and a deflecting system (30) arranged in the closed apparatus (12), and a light emitting surface (40) at the front face of the closed apparatus (12), said deflecting system (30) providing deflection of laser beam produced by said laser source (22) into pixels (42) of said light emitting surface (40), and a further deflection to direct laser ray emitted from said pixels (42) to various directions (i 1 , i 2  . . . i n ) defining a three-dimensional field of view, under control of synchronizing signal corresponding to direction information of a 3D video signal.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to a method and apparatus for producingthree-dimensional picture, in particular to a three-dimensionaltelevision receiving system. The invention is also useful for otherpurposes, such as industrial planning and design.

2. Summary of the Prior Art

Video signals are recorded electronically or by other means, and may bedisplayed through a television system. The television receiver convertsincoming television (video) signals into the original scenes or figuresalong with the associated sounds. The known two-dimensional televisionreceivers comprise a picture tube having plane or arched fluorescentscreen, producing a planar image by varying the electron-beam intensityas the beam, emitted by an electron gun, is deflected from side to sideand up and down to scan a raster on the fluorescent screen at the otherend of the tube. The fluorescent screen realizes a definite raster ofsegments, known as picture points or picture elements, arranged inscanning lines. The picture elements of the fluorescent screen arescanned point to point after each other by the electron beam, as theelectron beam is moved by controlled horizontal and vertical deflection.

The issue of displaying true 3D scenes is not yet solved properlyup-to-date. According to the present state of television technique 3Dimage reconstruction is exhausted at the level of displayingstereoscopic or autostereoscopic images. In these systems thethree-dimensional effect is based on the deception of human perception(e.g. using special glasses) causing bad physiological effect. There areexperimental systems which employ lenticular-lenses. By principle, thesesystems realize a resticted field of view and poor resolution.

A widely used method of three-dimensional optical image formation is theholography, a technique for recording and later reconstructing theamplitude and phase distributions of a wave disturbance. In opticalimage formation, the technique is accomplished by recording on a specialphotographic plate the pattern of interference between coherent lightreflected from the object figure, and light coming directly from thesame source or being reflected from a mirror. When the specialphotographic plate, known as hologram is developed and illuminated frombehind by a coherent laser beam, it produces a three-dimensional imagein space. Holography, however, is not a practical technique forproducing three-dimensional picture from video signals.

OBJECTS OF THE INVENTION

An object of the invention is to provide a method which enablesreceiving three-dimensional video signals and producing realthree-dimensional picture from them.

A further object is to develop an apparatus to realize the above method,i.e. an apparatus producing three-dimensional picture from the received3D video signal, said apparatus being realizable with reasonable formand expenditure. An essential object of the invention is to achieve athree-dimensional television system by means of the suggested method andapparatus.

SUMMARY OF THE INVENTION

An essential feature of all kind of two-dimensional, planar images, e.g.paintings, photoes or picture of a usual television screen is that theintensity of light emitted or reflected from any point of the picture isindependent, within a wide field of view, from the direction of theemitted or reflected light, i.e. a given picture point is the sameviewed from every direction. On the other hand, a three-dimensional,spatial picture is characterized by picture points emitting orreflecting different light beams in every direction of the field ofview, which means that the intensity (and colour) of a given picturepoint viewed from different directions depends on the viewing direction.

It has been found that a three-dimensional picture can be provided bymeans of a light emitting surface in which light beams are emitted fromthe picture points of said light emitting surface to many directions,wherein the intensity and colour of the light beam emitted from anypicture point is function of the viewing direction. Said viewingdirections together define a three dimensional field of view. Thequality of such three dimensional picture would depend on the density ofthe picture points and on the number of directions defining the field ofview, and also on the width of said field of view. There are two ways toachieve the above task, that is deflecting a modulated, spatiallycoherent light ray to get a 3D image. The one way is that the points ofthe light emitting surface are active light emitting elements, e.g. aLaser Diode Array, with the necessary optics and control means so thatthey can emit light of proper intensity and colour to the givendirections in a controlled way according to a 3D video signal. Accordingto the other way, light rays from one or more common light sources aredirected to the pixels and manipulated according to the importantcharacteristics of the light (intensity, colour and direction), at thecommon source or at the pixels.

Set out from the above recognition, one method according to theinvention comprises the steps of:

modulating the intensity of a spatially coherent light ray, preferably alaser ray by a 3D video signal (video signal containingthree-dimensional picture information),

directing the modulated laser ray by controlled deflection into pixelsdefining a light emitting surface, and

deflecting the modulated laser ray to be emitted from every pixel of thelight emitting surface to a number of directions, said directionsdefining a given field of view, the intensity of said laser raycomponents emitted from said pixels in various directions of the fieldof view corresponding to the direction information of the concerningdirection of the 3D video signal.

According to the invention the laser ray modulated with the 3D videosignal containing intensity and colour information is directed to thepicture points (pixels) in a defined order, which order is preferablycontrolled by the synchronizing components of said 3D video signal. Thelight ray emitted from any pixel to any direction has an intensity andcolour corresponding to the intensity and colour information of the 3Dvideo signal component associated with said pixel and said direction.

The coordinates of an emitted laser ray is defined as a result of thehorizontal, vertical and viewdirectional deflections.

Basicly there are two modes of achieving the above deflections ofmodulated laser ray according to picture points and directions.

The one mode is deflecting the laser ray according to said directionsbefore reaching the pixels so that the incident components of laser raystriking into the pixels are deflected in angle of arrival or displacedparallel in association with the direction they belong to. The furtherdeflection shall be achieved without any further controlled step,preferably by use of passive optical means.

According to the other mode of deflecting the laser ray strikes into thepixels without being deflected according to the view directions, and isdeflected and emitted through active, controlled optical elements placedin the pixels to said various directions defining said field of view.

The modulated laser can be directed into said pixels by means ofmechanical or acousto-optical deflecting means controlled in accordancewith said directions of the field of view, too, wherein said mechanicalor acousto-optical deflection is preferably controlled by horizontal andvertical deflection information contained in the synchorinizingcomponent of said 3D video signal.

Preferably, the modulated laser ray is directed into said pixels by useof horizontal and vertical (frame) deflection according to TV standards,said pixels being arranged so that their configuration conforms with thestandard TV picture point configuration.

In an advantageous practical mode of realizing the invention a laserbeam is modulated by a 3D video signal having no vertical parallaxinformation content, wherein said laser beam emitted from a pixelhorizontally sweeps along said field of view, said laser beam having adefinite vertical dispersion. Since the human eyes are normally in thesame horizontal plane, omitting the vertical parallax does not meanpractically any essential loss of quality in the three-dimensional view.

The modulated laser ray striking into said pixels preferablyholographic/diffractive can be deflected and directed throughholographic diffractive optical elements or through periodicalspheric-symmetrical optical elements to the directions of the field ofview.

According to the invention the modulated laser ray can be achieved bydirect modulation of a laser source with said 3D video signal.

The modulated laser ray can also be achieved by modulating anacousto-optical crystal through which the laser ray passes by said 3Dvideo signal.

A sufficiently wide spatial view can be achieved by realizing a field ofview of 30° to 150°, wherein the number of said various directionsdefining

said field of view is 30 to 150, which presumes a horizontal dispersionof emitted light beam of about 1°. Our experiments show thatthree-dimensional spatial picture of satisfactory quality is achievedeven with a horizontal viewing field of 30 to 40 degrees, and viewdirection steps of 1 to 3 degrees. As mentioned above, the verticalparallax of the three-dimensional view can be omitted. In this case thelaser beam of any horizontal direction should have an appropriatevertical dispersion, which can be achieved by using e.g. holographic orvertical cylindric-symmetrical optics combined with one dimensionaldispersion elements.

According to the invention colour three-dimensional picture can beproduced by modulating a multicoloured laser beam or more laser rays,preferably three laser rays of different basic wavelength (red, greenand blue), deflecting and directing them into said pixels, and directinga modulated laser beam containing said three laser rays of differentbasic wavelength from each pixel to each direction of said field ofview.

Three dimensional moving picture may be achieved according to theinvention by a definite number, preferably at least twenty picturerepetitions per seconds.

The bandwidth of the 3D video signal can be reduced if necessary by useof any data- or information-compressing process. Such processes areknown per se so the don't need further discussion.

The 3D video signal by which the laser beam is modulated can be producede.g. so that 2D images of a spatial scene or figure are takensimultaneously from each of said directions defining said field of viewby means of appropriate TV or video cameras, advantageously amultielement CCD camera containing a corresponding number of CCD chips,and the 2D signals recording the different view images are composed toconsitute a 3D video signal format. The signal components associatedwith the different picture points and various view directions areordered in a defined time sequence. Other means for recording a 3D videosignal are known per se.

According to another way, the problem of producing three-dimensionalpicture can also be solved by controlling spatially coherent elementarylight sources, such as CSD or monolithic surface-emitting laser diodearrays, or preferably elementary laser sources, arranged to constitute alight emitting surface, so that each of the elementary light sources iscontrolled according to the corresponding view direction information ofa 3D video signal, wherein said view directions define a given field ofview.

In this case preferably each of said elementary light sources isassociated with one of said view directions, and controlled according tothe one direction it belongs to. The light rays emitted by saidelementary light sources are directed to the view direction thecorresponding elementary light source belongs to, by use of opticalmeans integrated in the pixels of said light emitting surface.

The elementary laser sources can also be simultaneously controlled incombination with each other according to holographic patterns, so thatthe laser beams sent to said view directions are achieved by theinterference of coherent light waves emitted by the elementary lasersources.

In order to reduce the sharp resolution requirements of the deflectionsystem used in carrying out of the invention, a further method issuggested, employing a light beam comprising independently controllablecoherent light rays; The suggested method comprises the steps of:

modulating a coherent light beam, preferably a laser beam by a 3D videosignal, wherein the modulated light beam should contain light rays eachassociated with a view direction, said view directions defining a givenfield of view, said light rays of the beam being modulatedsimulaneously, each light ray according to its associated viewdirection,

directing said modulated coherent light beam into pixels arranged todefine a light emitting surface, and

emitting each component of the modulated coherent light beam from thepixels to the direction said component (light ray) is associated with.

The invention also relates to an apparatus for producingthree-dimensional picture. The apparatus according to the inventioncomprises:

a spatially coherent light source, preferably laser source;

a modulator to modulate laser ray produced by said light source, saidmodulator controlled by a 3D video signal;

a deflecting sysem to deflect modulated laser ray, controlled by thesynchronizing signal of the 3D video signal;

a light emitting surface composed of pixels of definite mutualarrangement; and

optical elements adjusted in said pixels of the light emitting surfaceto deflect when transmitting or reflecting incident laser ray from thepixels to various directions, said directions defining a given field ofview, wherein said deflecting system is controlled to deflect laser rayin accordance with said directions of the field of view into saidpixels.

Preferably, the pixels constituting the light emitting surface arearranged in conformity with the picture point configuration of astandard TV screen, and said deflection system comprises horizontal andvertical deflection units controlled by the line synchronizing signaland frame synchronizing signal, respectively, of the 3D video signal.The vertical deflection unit and the horizontal deflection unit cancomprise e.g. acousto-optical crystals controlled by voltage-controlledoscillators.

The deflecting system may involve acousto-optical elements controlled inaccordance with the directions of said field of view. The opticalelements can also be passive elements of pre-defined horizontaldeflection characteristic and definite vertical dispersion, preferablycylindric-optical elements, holographic optical elements etc., saidholographic optical elements having vertical focus line, and lightdispersing in vertical planes involving said vertical focus line. In thelatter case, when the optical elements in the pixels are passive ones,the deflecting system provides that the laser ray arriving the pixels isdeflected according to the various directions. The deflection range ofsaid deflection system should correspond to the number and width of saidoptical elements adjusted in said pixels.

In a preferred apparatus according to the invention the deflectionsystem comprises fibreglass groups, one for each pixel, said fibreglassgroups each having a number of fibreglasses, which number is equal tothe number of various directions defining said field of view, the inputend of said fibreglass groups being attached to the output of a unitdeflecting said modulated laser ray in accordance with the pixels, theother end of said fibreglass groups being attached to the concerning oneof said pixels, the end sections of the fibreglasses of said groupsbeing adjusted to direct laser ray to the very direction associated withthe corresponding one of said fibreglasses. Each fibreglass of a grouptransmits a component of the modulated laser beam, which component isassociated with the view direction said fibreglass belongs to.

In a further preferred embodiment of the invention the laser source andsaid modulator are realized in a laser unit comprising laser diodecontrolled by said 3D video signal. A more practical construction can beachieved by integrating said laser source, modulator and deflectionsystem in an integrated optical unit.

In a preferred embodiment of the invention the laser source is directedto an acousto-optical modulator crystal which is controlled by said 3Dvideo signal through a signal forming unit.

The apparatus according to the invention can be appropriate to reproducecolour spatial image, in which case it comprises multicolour lasersources or more, e.g. three laser sources of different basic wavelength.Either there is one optical element in each pixel and electronicallycopmensated deflection applied, or there are three optical elementsarranged in each pixel to deflect or transmit the incident laser ray ofcorresponding wavelength to the various directions defining said fieldof view.

A further preferred embodiment of the invention comprises:

control means for receiving 3D video signal,

a light emitting surface constituted by pixels,

spatially coherent elementary light sources, e.g. CSD-s or elementarylasers (e.g.) MSELDA arranged in said pixels, to emit coherent lightrays of appropriate direction-related intensity to directions defining agiven field of view.

In a preferred embodiment of the above apparatus each of said elementarylasers is associated with at least one of said directions defining saidfield of view. This feature can also be achieved so that there areoptical elements adjusted in said pixels of the light emitting surface,each of said optical elements directing the laser ray emitted by one ofsaid elementary lasers to the direction said elementary laser isassociated with.

In another preferred embodiment the distances between adjacentelementary lasers are in order of magnitude of the light wavelength, sothat the laser rays emitted by said elementary lasers interfere witheach other in accordance with a holographic control of the whole set ofsaid elementary lasers.

The apparatus according to the invention can realize a three-dimensionaltelevision receiver or video or computer monitor comprising a closedreceiver apparatus having 3D video input and/or arial input, whereinsaid laser sources, modulator an deflecting system are placed in thebottom part of the closed apparatus, said light emitting surface isarranged along the front face of the closed apparatus, and saiddeflecting system is connected with the optical elements of said lightemitting surface through focusing scanner mirror optics arranged behindthe light emitting surface, inside of said closed apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated hereinafter with reference to theaccompanying drawings in which:

FIG. 1 is a block diagram of a system illustrating a way of carrying outof the invention;

FIG. 1A is a light intensity diagram of a laser beam modulated by theluminescence signal component of a 3D video signal;

FIG. 1B is a voltage diagram of the luminescence signal component of a3D video signal modulating a laser beam in the system of FIG. 1;

FIG. 2 is a schematic diagram of a preferred embodiment of theinvention;

FIG. 3 is a schematic diagram of an embodiment of the deflection systemand light emitting surface employed in a system according to theinvention;

FIG. 4 is a schematic diagram illustrating the function mode of anotherpreferred embodiment of the deflection system and light emittingsurface;

FIGS. 5A and 5B are schematic diagrams illustrating the function mode ofa pixel of the light emitting surface, in case of providing and notproviding vertical parallax, respectively;

FIG. 6 is a schematic diagram illustrating the function mode of apreferred embodiment of the invention, providing no parallax, and thelaser beam emitted from a pixel of the light emitting surface having adefinite dispersion in vertical plane;

FIG. 7 is a block diagram of a further preferred embodiment of theinvention;

FIG. 8 is a schematic perspective view and illustration of function ofthe apparatus of FIG. 7;

FIGS. 9A and 9B are schematic diagrams illustrating two preferred way ofmodulating laser ray in a system according to the invention;

FIGS. 10A and 10B are schematic, partly block diagrams of preferred waysof carrying out the deflection of laser ray according to the invention;

FIG. 11 is a schematic view of the preriodical cylindric optical elementemployed in the deflection system of an apparatus according to theinvention;

FIG. 12 is a schematic view of a holographic optical element arranged ina pixel of the light emitting surface of an embodiment of the invention;

FIG. 13 is a schematic diagram illustrating the function mode of apreferred way of carrying out of the invention;

FIG. 14 is a schematic top view of a part of the light emitting surface,illustrating a mode of function of an optical element arranged in apixel of the light emitting surface;

FIG. 15 is a schematic top view of a light emitting surface,illustrating a three dimensional visual field achieved by the invention;

FIG. 16 is a schematic top view of an arcuate light emitting surface,providing a wider three dimensional visual field;

FIG. 17 is a schematic diagram of a preferred embodiment of theinvention providing three dimensional colour picture;

FIG. 17A is an enlarged front view of a pixel of the light emittingsurface of the apparatus of FIG. 17;

FIGS. 18A and 18B are schematic side sectional and front sectionalviews, respectively, of a three-dimensional television receiver setaccording to the invention;

FIG. 19a is a schematical view of an apparatus for recording 3D videosignal;

FIG. 19b is a schematic plan view illustrating the function of theapparatus for recording 3D video signal;

FIG. 19c is a schematic plan view illustrating a display arrangement fordisplaying the recorded 3D video signal;

FIGS. 20a and 20b are intensity diagrams of a two-dimensional andthree-dimensional video signal, respectively;

FIG. 21 is a schematic perspective view of a part of an embodiment ofthe light emitting surface of a further embodiment of the invention; and

FIG. 22 is a schematic top view of pixels of the light emitting surfaceof FIG. 21.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring first to FIG. 1, an apparatus 10 for carrying out theinvention comprises a laser and modulator unit 20, a separator unit 21,a deflection system 30 and a light emitting surface 40 having pixels 42arranged in a defined configuration. The input signal is a 3D videosignal which is separated by separator unit 21 to luminescence andcolour signal component and synchronizing signal component. Thesynchronizing signals are applied to the control input of the deflectionsystem 30, while the luminescence and colour signals control the laserand modulator unit 20, modulating a laser beam according to thethree-dimensional picture information. From the output of laser andmodulator unit 20 a modulated laser beam is applied to a deflectionmeans 34 which directs the incoming laser beam by controlled deflectioninto the pixels 42 of the light emitting surface 40, into each pixel 42subsequently after each other.

The deflection system also comprises deflection means 36 providing atime controlled deflection of the laser beam arriving in the pixels 42to various directions i₁, i₂ . . . i_(n) of a given field of view. Anessential feature of the invention is that the pixels 42 of the lightemitting surface should emit laser beam to each direction withcorresponding intensity and colour, in contrast with the two-dimensionalscreen, where the intensity and colour of the light emitted from anypicture point is direction invarious.

In order to achieve laser beam emission of direction various intensityit is necessary to have the laser beam modulated corresponding tovarious directions and have a deflection controlled in accordance withthose directions. As illustrated in FIG. 1A and 1B, respectively, theluminescence signal component of a 3D video signal, and so the modulatedlaser signal have time sections corresponding to the various picturepoints, i.e. pixels 42, and each section corresponding to any of thepixels has subsections, each associated with one of the directions i₁,i₂ . . . i_(n).

For comparison purposes, FIGS. 20a and 20b illustrate a two-dimensionaland a three-dimensional video signal, respectively. As seen in thefigures, the 2D video signal is substantially constant within a sectioninterval corresponding to a picture element, while the 3D video signalcomprises subsections of different amplitude even within one sectioninterval, each of said subsections corresponding to a definite viewdirection.

In the embodiment of FIG. 2 the deflection system 30 comprisesdeflection means 36 composed of fibreglass-groups 37. Each pixel 42 isassociated with one of the fibreglass-groups 37, each of them comprisinga number of fibreglasses, which number is equal to the number n ofdirections i₁, i₂ . . . i_(n). The modulated laser beam applied to thedeflection means 34 is forwarded to the input and of saidfibreglass-groups 37 so that each section of the modulated laser beamcorresponding to one of the pixels 42 arrives at the input of thefibreglass-group 37 which is associated with that of pixels 42. The endsections of the fibreglasses are arranged so that the laser beam emittedfrom the fibreglasses, that is emitted from the pixel is directed to thecorresponding one of directions i₁, i₂ . . . i_(n). If necessary, acorrecting optical deflection can be employed in the pixels 42, in orderto exactly meet the defined directions i₁, i₂ . . . i_(n).

The function of the deflecting system illustrated in FIG. 3 basiclydiffers from the above embodiment. In this deflecting system themodulated laser beam arrives the pixels only deflected by deflectionmeans 34, without being deflected according to the various directionsi₁, i₂ . . . i_(n). This second deflection is carried out in the pixels42, by means of active optical elements, preferably acousto-opticalelements, controlled by a radio-frequency generator 31 corresponding tothe various directions i₁, i₂ . . . i_(n). The input of the RF generatoris driven by an appropriate saw-tooth signal.

FIG. 4 shows a further possible way to achieve deflection to the variousdirections according to the invention. Passive optical deflectionelements are arranged in the pixels 42. The modulated laser beam strikesthe pixels 42 parallel displaced in time, so that the subsections of thelaser signal corresponding to the different directions arrive thepassive optical element in the pixel 42 in a defined shift position, sothat each subsection of the laser signal will be deflected by thepassive optical element to the corresponding one of said directons.

FIG. 5A illustrates how the laser beam, in time sequence, is emittedfrom a pixel 42 to various directions defining a three-dimensional fieldof view, in case of producing three-dimensional picture from a 3D videosignal comprising vertical parallax. For such a three-dimensionalemission optical elements of spherical symmetry or holographic opticalelements can be used. In the practice, however, the vertical parallaxinformation may be omitted without significant restriction of thethree-dimensional image, as illustrated in FIG. 5B. In order that theviewing height, i.e. the vertical position of the viewer's eyes be notso critical, the laser beam modulated by a 3D video signal having novertical parallax shall be emitted to various directions of a horizontalfield of view, and dispersed in vertical planes, involving saiddirections as shown in FIG. 6. For such purpose e.g. cylindrical opticalelements or holographic optical elements are the appropriate deflectionmeans.

The block diagram of FIG. 7 basicly differs from the system of FIG. 1 inthat the light emitting surface 40 of FIG. 7 is a separate functionalelement, not part of the deflection system 30. Laser and modulator unit20 comprises a laser source 22 and a modulator 24, as shown in FIG. 8.Modulator 24 is controlled by a luminescence and colour signal componentIN of the 3D video signal. The modulated laser beam is deflected to thepixels 42 of the light emitting surface 40 and deflected or paralellydisplaced corresponding to various view directions, according to adefined time sequence, by means of a deflection system 30 controlled bythe synchronizing signal component SY of the 3D video signal.

FIG. 9A shows a preferred embodiment of laser and modulator unit 20,comprising an integrated unit of a semiconductor laser diode 27 and chip29 attached to forming optics 28. The output signal is a modulatedcoherent laser beam, the intensity I of which being also illustrated inFIG. 9A.

FIG. 9B illustrates another preferred way of producing modulated laserbeam, wherein a continuous laser source 22 sends laser beam to amodulator 24 carried out as acousto-optical crystal controlled by a 3Dvideo signal through a radio-frequency generator 26.

FIG. 10A and 10B show preferred embodiments of a part of deflectionsystem 30, providing synchronized deflection of a modulated laser beamL_(m) to pixels 42 of the light emitting surface 40, according to aprescribed time sequence. In the examples the geometrical and sequentialarrangement of the pixels 42 corresponds to the picture elementconfiguration of a standard two-dimensional television screen, so thedeflection unit 34 comprises horizontal (line) deflection unit 33 andvertical (frame) deflection unit 32, similarly to the deflection systemof known TV-s. In FIG. 10A deflection units 32 and 33 are polygonalmirror arrangements driven by precisely controlled motors not shown inthe drawings.

In FIG. 10B the horizontal and vertical deflections are provided byacousto-optical crystals controlled by voltage-controlled oscillators 38and 39, driven by saw-tooth generators.

Referring now to FIGS. 11 and 12, optical elements 44 arranged in pixels42 of the light emitting surface 40 are shown. In FIG. 11 opticalelements 44 are realized as periodical cylindric-symmetrical optics,while optical elements of FIG. 12 are holographic optics, such astransmissional relief holograms. Holographic optical elements arearranged on a planar carrier plate, preferably made out of colouredglass or plastic. In case of choosing appropriate optical elements, thewhole light emitting surface 40 can be produced by a single pressingmethod.

As illustrated in FIG. 13, a modulated, focused laser beam strikes apixel 42 so that it arrives, shifted in time, at n different points ofthe holographic optical element 44 set in the pixel 42. The direction towhich the laser beam is emitted from the pixel 42 depends on where thelaser beam strikes the incidence surface of the optical element 44. Asthe point of incidence moves along the inner surface of the opticalelement 44, the direction of the emission of the laser beam changesbetween directions i₁ and i_(n), so that the emitted laser beam sweepsalong a field of view α, defined by said directions i₁ . . . i_(n).

In order to achieve a continuous three-dimensional image the laser beamemitted from a pixel to a defined direction shall have a defined angleof divergence δ. In a simple case for example the field of view α isequal to 90°, and there are 90 different directions i₁, i₂ . . . i₉₀within the field of view, wherein the angle of divergence δ of theemitted laser beam shall be about 1°.

FIG. 14 illustrates the function of another kind of light emittingsurface 40. The deflection system provides parallel displacement of thelaser beam striking the pixels, so that each relative position of thestriking laser beam within a pixel 42 corresponds to one of the viewdirections i₁ . . . i_(n). The laser beam striking a given point of theoptical element 44 in a pixel 42 at the moment t_(k) will be deflectedby the optical element in a direction 44 i_(k) corresponding to thepoint of incidence. As the point of incidence moves along the surface ofthe optical element 44 in a pixel, the emitted laser beam sweeps alongthe whole field of view α. Here the optical elements are convergentoptics, while the similar system of FIG. 4 comprises divergent opticalelements.

FIGS. 15 and 16 illustrate the formation of the field V of fullthree-dimensional visual image. The field V is considerably ider in caseof FIG. 16, where an arcuate, concave shaped light emitting surface 41is employed. Similar feature can be simulated more practically by use ofa plane screen having pixels with changing properties.

Referring now to FIGS. 18A and 18B, an example of a three dimensional TVset, carried out as a preferred embodiment of the apparatus according tothe invention. The television receiver apparatus 12 comprises a closedbox having a front face realizing a screen-like light emitting surface40. Inside the closed box there is arranged focusing scanner mirroroptics 14 to reflect a modulated laser beam into the pixels of saidlight emitting surface 40. In the bottom part of the closed apparatusthere is arranged a multicolour laser and modulator unit 20 anddeflection units of a deflection system 30. The apparatus can be used asa three-dimensional video or computer monitor with a 3D video input oras a television receiver with a 3D television signal/arial input.

FIGS. 17 and 17A show by way of example only the principle of athree-dimensional colour monitor accomplished according to theinvention. The colour apparatus comprises at least three laser sources22R, 22G and 22B, each of different basic wavelength (red, green andblue). In the pixels 42 there are arranged above each other threedeflecting optical elements 44R, 44G and 44B for each laser beam ofdifferent colour, to form and emit a light beam of definite colour tothe corresponding directions.

In a preferred embodiment the width of the optical elements 44R, 44G and44B is about 0.5 mm, while their height is about 0.15 mm. Opticalelements 44R, 44G and 44B are preferably realized by holographic opticalelements.

FIGS. 19a and 19b illustrate a picture recording apparatus for producinga 3D video signal without vertical parallax, as shown in FIG. 20B. Theapparatus comprises a number of 2D recording cameras C1, C2 . . . Cn,e.g. CCD chips with optical supplement arranged next to each other inhorizontal plane in a fixed mutual position, in accordance with the viewdirections of the displaying system, in a similar way as stereograms arerecorded. The number of said cameras is equal to the number n of theview directions. Pictures of a spatial figure or scene are taken by thecameras C1, C2 . . . Cn simultaneously from different view directions,and the 2D video signals recorded by the 2D cameras are subsequentlyordered in a pre-defined way to achieve a 3D video signal format. Duringrecording a virtual screen, marked by reference numeral 1 shall beconsidered, the relative position of which corresponding to that of thelight emitting surface of the 3D display system, as illustrated in FIGS.19b and 19c, respectively. FIG. 19c demonstrates that the light signalreceived from a same point of the light emitting surface 40 by the lefteye L of a viewer is different from the light signal received by theright eye R.

FIG. 21 and 22 illustrate the principle and function of a further way ofcarrying out the invention. In a light emitting surface 40' comprisingpixels 42, there is a number of spatially coherent elementary lightsources, preferably elementary lasers 50 arranged in each pixel 42'. Theelementary lasers 50 are controlled to emit light signals to eachdirection of the field of view. In a preferred embodiment eachelementary laser 50 of a pixel 42' belongs to a defined view direction,being controlled by a 3D video signal to emit laser beam ofcorresponding intensity and colour to the related direction.

In another possible embodiment the elementary lasers 50 are mutuallyarranged so that the distances between adjacent elementary lasers 50fall in the order of magnitude of light wavelength. In this case theelementary lasers 50 are controlled simultaneously in a holographic way,so that the light beams emitted by said elementary sources interferewith each other to provide light beams of corresponding intensity andcolour to each direction, according to the 3D video signal control. Suchholographic control programs are known per se.

FIG. 22 shows that the direction of the light beams emitted by theelementary lasers 50 can be deflected to meet the desired view direcionsby means of optical elements 44', locatd in the pixels 42'.

What we claim is:
 1. A method for producing a three-dimensional picture,comprising the steps of:modulating a coherent light beam by athree-dimensional video signal to obtain light rays containing pictureinformation and each associated with a view direction; and directing themodulated light beam to pixels arranged to define a light emittingsurface; wherein each light ray of the modulated coherent light beam isemitted from an associated pixel in the associated view direction. 2.Apparatus for producing a three-dimensional picture, comprisinga laser;a modulator for modulating laser rays produced by said laser so that thelaser rays include picture information, said modulator controlled by avideo signal containing three-dimensional picture information; adeflecting system for deflecting the modulated laser rays and controlledby a synchronizing signal for the video signal; and a light emittingsurface composed of pixels in a fixed arrangement, the pixels containingoptical elements that deflect and transmit incident laser rays in aplurality of view directions (i₁, . . . i_(n)) for each said pixel, saidview directions defining a given field of view (a), wherein saiddeflecting system is controlled to deflect the modulated laser rays tosaid pixels.
 3. The apparatus claimed in claim 2, wherein said opticalelements are passive elements having constant horizontal deflection anddefinite vertical dispersion in vertical planes.
 4. Apparatus forproducing a three-dimensional picture, comprising:a laser; a modulatorfor modulating laser rays produced by said laser, said modulatorcontrolled by a video signal containing three-dimensional pictureinformation; a deflecting system for deflecting the modulated laser raysand controlled by a synchronizing signal of the video signal; and alight emitting surface composed of pixels in a fixed arrangement, thepixels containing optical elements that deflect and transmit incidentlaser rays in a plurality of view directions (i₁ . . . i_(n)) for eachsaid pixel, said view directions defining a given field of view (α),wherein said deflecting system is controlled to deflect the modulatedlaser rays to said pixels and wherein said optical elements of each saidpixel are acousto optical elements controlled to emit light in the viewdirections (i₁ . . . i_(n)) indicated by a radio frequency generator. 5.Apparatus for producing a three-dimensional picture, comprising:a laser;a modulator for modulating laser rays produced by said laser, saidmodulator controlled, by a video signal containing three-dimensionalpicture information, a deflecting system for deflecting the modulatedlaser rays and controlled by a synchronizing signal of the video signal;and a light emitting surface composed of pixels in a fixed arrangement,the pixels containing optical elements that deflect and transmitincident laser rays in a plurality of view directions (i₁ . . . i_(n))for each said pixel, said view directions defining a given field of view(α), wherein said deflecting system is controlled to deflect themodulated laser rays to said pixels and said deflection system furthercomprises a group of fibreglass elements for each pixel, said fibreglassgroups each having a number of fibreglass elements equal to the number(n) of the plurality of directions (i₁ . . . i_(n)) defining said fieldof view (α), the input end of said fibreglass groups being attached tothe output of a deflection unit, the fibreglass elements at the outputend of said fibreglass groups adjusted to direct the laser rays to theplurality of view directions.
 6. A method for producing athree-dimensional picture, comprising the steps of:modulating theintensity of a spatially coherent laser ray by a video signal containingthree-dimensional picture information such that the modulated coherentlaser ray includes picture information; and emitting said modulatedlaser ray from points of a light emitting surface in a plurality ofdirections defining a given field of view, the instant value of theintensity of the modulated laser ray emitted from the points of thelight emitting surface in any one of said plurality of directionscorresponding to the three-dimensional picture information defining theemitted direction.
 7. The method of claim 6, wherein the emitting stepfurther includes the step of deflecting the modulated laser ray to thepoints of the light emitting surface for emission therefrom in theplurality of directions.
 8. The method of claim 6, wherein the modulatedlaser ray is deflected to strike the points of the light emittingsurface in such a distinguishing position or at such distinguishingangles of incidence that incident time components of the laser ray aredeflected through passive optical elements.
 9. The method of claim 6,wherein the modulated laser ray is deflected to the points of the lightemitting surface and emitted through active, controlled optical elementslocated in the pixels.
 10. The method of any of claims 6, 8, or 9,wherein said modulated laser ray is directed into the points of thelight emitting surface, preferably onto periodical spheric orcylindric-symmetrical refractive or diffractive optical elementsarranged in the points of the light emitting surface by use ofhorizontal and vertical (frame) deflection according to TV standards,the points of the light emitting surface being arranged so as to conformwith standard TV picture point configuration.
 11. The method of any ofclaims 6, 8, or 9, wherein the three-dimensional video signal containsno vertical parallax information and wherein said emitted laser rayshorizontally sweep along the field of view with a definite verticaldispersion.
 12. The method of claim 6, wherein said three-dimensionalvideo signal comprises a plurality of two-dimensional images of aspatial scene, each two-dimensional image corresponding to one of theplurality of directions within the field of view, and thetwo-dimensional images being arranged subsequently according to saiddirections to form the three-dimensional video signal.
 13. The method ofclaim 6, wherein said modulated laser ray is deflected to strike thepoints of the light emitting surface so that an angle of incidence ofthe laser rays correspond to the plurality the directions.